Natalizumab is a recombinant humanized monoclonal antibody targeting α4-integrin. It exerts its therapeutic effect by inhibiting the migration of immune cells but may cause severe immune-related adverse reactions.

Precautions for Taking Natalizumab

High-Risk Populations

Pregnancy: Animal studies have shown that it may affect fetal development (e.g., thrombocytopenia), so the necessity of treatment needs to be evaluated.

Lactation: Whether the drug is excreted in breast milk is not yet clear; it is recommended to discontinue the drug or terminate breastfeeding.

Children and the elderly: The safety in patients under 18 years of age has not been established, and data on populations over 65 years of age are limited.

Prevention and Control of Infusion-Related Risks

Allergic reactions: Approximately 1.3% of patients experience severe systemic reactions, most of which occur within 2 hours of infusion. Symptoms include urticaria, hypotension, dyspnea, etc. Immediate drug discontinuation and emergency treatment are required.

Operational specifications: The infusion time should be ≥ 1 hour, and the patient should be observed for 1 hour after the infusion is completed. Intravenous push or rapid infusion is prohibited.

Immunosuppression and Infection Risks

Concurrent medication: Concurrent use with other immunosuppressants (e.g., azathioprine) is prohibited, as it may increase the risk of opportunistic infections.

Infection management: The infection rate in clinical studies was approximately 1 case per patient-year, mainly involving respiratory tract and urinary tract infections. If an active infection occurs, drug administration should be suspended.

Drug Preparation and Storage

Dilution requirements: 300mg of the drug needs to be diluted with 100mL of 0.9% sodium chloride; the use of other solvents is prohibited.

Stability: After dilution, the drug can be stored at room temperature for ≤ 8 hours and refrigerated for ≤ 24 hours; freezing or shaking should be avoided.

Medication Monitoring for Natalizumab

Laboratory Indicators

Complete blood count: Monitor the increase in lymphocytes and monocytes (a drug effect); changes in neutrophils indicate possible infection.

Liver function: Test ALT/AST at baseline and every 3 months; if the abnormal value is ≥ 3 times the upper limit of normal (ULN), drug use should be suspended.

Thyroid function: Regularly monitor TSH and free T4 (the incidence of thyroiditis is approximately 6%).

Immunogenicity Monitoring

Antibody testing: Screen for anti-drug antibodies every 12 weeks; approximately 10% of patients develop antibodies (6% are persistent).

Impact: In patients with positive antibodies, the serum drug concentration drops sharply (< 1 mcg/mL vs. 17 mcg/mL), and the therapeutic effect is significantly reduced.

Management: Patients with persistent positive antibodies need to discontinue the drug to avoid the risk of subsequent infusion reactions.

Imaging and Clinical Symptom Tracking

MRI assessment: Monitor T1 gadolinium-enhancing lesions and T2 hyperintense lesions annually to evaluate disease activity.

Neurological function: Conduct regular EDSS (Expanded Disability Status Scale) scoring and combine it with the frequency of relapses.